Modern cellular networks increasingly implement communication services to user equipment (UEs) through access nodes that have overlapping cell coverage areas, such as via a macro node (e.g., macro base station) that provides service to a relatively large cell coverage area, and one or more low power nodes (LPNs) (e.g., femto cells and pico cells) each of which provides service to a relatively small cell coverage area. The cell coverage area of the macro node may substantially overlap the cell coverage areas of one or more of the LPNs, and may even completely encompass the cell coverage areas of the one or more LPNs. The use of LPNs allows a service provider to ensure a good signal or relatively high bandwidth to a UE under circumstances where it would be difficult, impossible, or impractically expensive to do so with only relatively high-power macro nodes. This type of cellular network may be referred to as a heterogeneous network (HetNet).
LPNs may operate in different modes. Open access operating mode (OAOM) LPNs accept a handover from any subscriber UE. Hybrid access operating mode (HAOM) LPNs typically provide access to only UEs that are registered as members of the LPN, but will also provide access to non-member UEs based on certain criteria. A closed access operating mode (CAOM) LPN provides access only to UEs that are registered as members of the CAOM LPN. A Closed Subscriber Group (CSG) Long Term Evolution (LTE) LPN is an example of such a CAOM LPN.
While, as discussed above, the use of LPNs offer advantages, it has been determined that a CAOM LPN can cause interference with a UE that is proximate to the CAOM LPN but is not a member of the CAOM LPN and is therefore being served by a macro node. In particular, a major source of interference from such CAOM LPNs in an LTE HetNet is the CAOM LPNs transmission of cell-specific reference signals (CRS). Such interference can reduce the quality of the link between the UE and the macro node, and result in service outages, degraded communication links, and the like.
Some newer UEs include interference cancellation capabilities that help mitigate interference caused by the transmission of CRS. However, such interference cancellation capabilities are relatively complex, increasing the cost of the UE, and the mechanisms involved take away part of the useful signal, resulting in a lower Signal to Interference-plus-Noise Ratio (SINR) of the link between the UE and the macro node serving the UE. Moreover, legacy UEs do not have such interference cancellation capabilities. Accordingly, there is a need for additional mechanisms for facilitating communication between UEs and CAOM LPNs under certain circumstances.